Biochemical properties and expression profile of human prolyl dipeptidase DPP9

Hung Kuan Tang, Hsiang Yun Tang, Shu Ching Hsu, Yue Ru Chu, Chia Hui Chien, Chin Hang Shu, Xin Chen

Research output: Contribution to journalArticlepeer-review

24 Scopus citations


Dipetidyl peptidase 9 (DPP9) is a prolyl dipeptidase preferentially cleaving the peptide bond after the penultimate proline residue. The biological function of DPP9 is unknown. In this study, we have significantly improved the yield using Strep·Tactin® purification system and characterized the biochemical property of DPP9. Moreover, the dimer interaction mode was investigated by introducing a mutation (F842A) at the dimer interface, which abolished the enzymatic activity without disrupting its quaternary structure. Furthermore, DPP9 was found ubiquitously expressed in fibroblasts, epithelial, and blood cells. Surprisingly, contrary to previous report, we found that the expression levels of DPP8 and DPP9 did not change upon the activation of the PBMC or Jurkat cells. These results indicate that the biochemical property of DPP9 is very similar to that of DPP8, its homologous protease. DPP9 and DPP8 are likely redundant proteins carrying out overlapping functions in vivo.

Original languageEnglish
Pages (from-to)120-127
Number of pages8
JournalArchives of Biochemistry and Biophysics
Issue number2
StatePublished - 15 May 2009


  • Dimerization
  • Dipeptidyl peptidase
  • DPP9
  • Substrate specificity


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